1. Field of the Invention
This invention relates to lens barrier modules to be downsized, and more particularly, to a lens barrier module located at a front face of a lens body tube so as to protect an image pickup lens.
2. Description of the Related Art
Conventionally, there have been cameras with the lens barrier function to protect the lens from dust or the like entering from the outside. Generally, the lens barrier is integrally formed at a front face side of a lens body tube, and protects the lens in the lens body tube, for example, by closing sectors (blades) swingably provided. For instance, Japanese Patent Application Publication No. 3-186828 discloses a shutter apparatus having a lens barrier, and proposes a technique of driving the sectors for the shutter or lens and driving the lens barrier by means of one actuator. The lens barrier of the shutter apparatus has a configuration in which the lens barrier is moved through a pinion, gear, cam, and actuating lever.
The shutter apparatus of Japanese Patent Application Publication No. 3-186828, however, the drive motor of the sectors for shutter or the lens is also used for driving the lens barrier. For this reason, the drive mechanism such as a motor or the like extends long in the lens body tube from the proximity of the location of the sectors for the shutter to the lens barrier mechanism at an end of the lens body tube. Also, the shutter apparatus is provided with a switch mechanism switching the drive motor of the sectors for shutter or the lens and the barrier drive. This causes the drawbacks in that the structure of the lens body tube including the lens barrier function is complicated, and the size thereof is increased. Also, the lens barrier mechanism is integrally incorporated into the chassis and cannot used for another lens body tube, lacking in versatility.
In addition, the lens barrier of the shutter apparatus is opened or closed through the cam and the operation lever, thereby making it difficult to hold the barrier (sectors) at a closed or open position stably. Accordingly, in order to prevent and unstable movement of the sectors, there may be separately provided a stopper mechanism that retains the operation lever or the sectors at a stop position. However, such separately provided stopper mechanism will further lead to drawbacks in that the lens barrier mechanism is complicated and the size thereof is increased.